The present invention provides novel compounds, novel compositions, methods of their use and methods of their manufacture, such compounds pharmacologically useful in the treatment of cardiac arrhythmias. More specifically, the compounds of the present invention are Class III antiarrhythmic agents which, by effectively prolonging repolarization of a cardiac cell action potential, can be used effectively to treat certain cardiac arrhythmias.
Antiarrhythmic drugs have been grouped together according to the pattern of electrophysiological effects that they produce and/or their presumed mechanisms of action. Thus, Class I antiarrhythmic agents are characterized by being sodium channel blockers, Class II antiarrhythmic agents are beta adrenergic blockers, Class III antiarrhythmic agents prolong repolarization, and Class IV antiarrhythmic agents are calcium channel blockers.
Currently, there are very few Class III antiarrhythmic agents available for therapeutic use. Among them is bretylium. Bretylium's usefulness is limited, however, and currently its theraputic use is reserved for life-threatening ventricular arrhythmias that are refractory to other therapy. Thus, bretylium's use is generally confined to intensive care units. It is an object of this invention to provide Class III antiarrhythmic agents of broader theraputic use than existing Class III antiarrhythmic agents.